Substantial progress has been made in the development of efficacious treatments for adolescent depression. However, even when depressed adolescents receive the best treatments delivered under optimal circumstances, there is a great deal of heterogeneity in treatment response. There is a significant need for specific evidence-based clinical guidelines to direct clinicians in personalizing their patients' treatments to optimize their chances of reaching remission and minimizing burden. These guidelines, often referred to as adaptive treatment strategies, provide decision rules that recommend when, how, and for whom treatment should change. The purpose of this Mentored Patient-Oriented Research Career Development Award (K23) is the acquire expertise necessary to become an independent clinical interventions researcher with a focus on personalized treatment for adolescent depression. To achieve this goal, formal coursework and consultation with established experts are proposed in the following areas: (1) the development, implementation, and evaluation of combined psychosocial and pharmacological treatments for adolescent depression, (2) the development, implementation, and evaluation of strategies for personalizing treatment based on individuals' characteristics and treatment responses, and (3) advanced statistical methods for clinical trials. To complement these training activities, the candidate proposes to conduct a pilot sequential multiple assignment randomized trial (SMART) to develop an adaptive treatment strategy for adolescent depression that will operationalize when to make the determination that a patient treated with Interpersonal Psychotherapy for Depressed Adolescents (IPT-A) is not likely to reach remission if the treatment is continued and what the next treatment strategy should be. The feasibility and acceptability of the adaptive treatment strategy will be assessed, and exploratory analyses of treatment outcomes will be used to inform further development of the adaptive treatment strategy that will be tested in a subsequent R01 application.